code: def test_load_file(self):
      dat0 = np.random.rand(10, 1, 4, 4)
      dat1 = np.random.rand(10, 1, 4, 4)
  
      with tempfile.TemporaryDirectory() as tempdir:
          npzfile = f"{tempdir}/test.npz"
  
          np.savez_compressed(npzfile, dat0=dat0, dat1=dat1)
  
          npzds = NPZDictItemDataset(
              npzfile, {"dat0": "images", "dat1": "seg"}
          )
  
          item = npzds[0]
  
          np.testing.assert_allclose(item["images"].shape, (1, 4, 4))
          np.testing.assert_allclose(item["seg"].shape, (1, 4, 4))
  
file_path: MONAI/tests/test_npzdictitemdataset.py
imports: from __future__ import annotations
  import tempfile
  import unittest
  from io import BytesIO
  import numpy
  from monai.data import NPZDictItemDataset
label_desc: Use image node_id 2 for calling the TestNPZDictItemDataset obj's underlying member method code with example usage: obj.test_load_file() without return types